There may be more than one object to be simulated in the system of infrared object background simulation. All useful information of real object are included, such as main properties of the plane body, sky background, man-made interference to missiles and so on. The information is produced independently by optical method, and the independent sources are compounded for homer to receive, which assure the reality of homer tracing the targets. Every object has different spectrum characteristics and energy characteristics during multi-object compounding process. Two multi-object compounding methods were introduced. Cellular-mirror compounding method is of reflection type. It can be applied to the wide spectrum with a complex technique. Optical cable compounding method is simple, which minimizes the size of the system. Both methods have satisfactory practical results.